The omni controller by cidex has been out of production for over a decade. But demand for this model continues to run high. The primary place to get an omni is on ebay. You can expect to pay $180 for a used one. There aren’t any new ones although parts are still available at some slot car raceways.

The omni uses bridge rectifiers to vary current by dropping voltage 1.2 volts at a time. Unlike diode controllers or Parma resistor controllers that must be tuned for every class of car, a voltage stepping controller divides voltage so the car doesn’t matter.